i was wondering if anyone else has had trouble keeping an erection while taking ritalin???? what could i do to fix the problem??

It is unfortunately a side effect for most stimulants. You might want to try another type, it might not have the same effect.
Are you on an SSRI (like prozac) too? They may make this problem worse.
If all else fails - Viagra??

Nope, not really, but Viagra works good I bet.. :X